Electrically heated knife



Oct. v9, 1945.

T. F. SAFFADY ELECTRICALLY HEATED KNIFE Filed nec. a, 1944 faz l III II-Ill Hui-dax;

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INI/ENTOR. TMM T5479@ BY j Patented Oct. 9, 1945 UNITED STATES PATENT' OFFICE ELECTRICALLY HEATED KNIFE Thomas F.. Saiady, Detroit, Mich.

Application December 8, 1944, Serial No. 567,244

(Cl. 21S- 21) 2 Claims.

This application relates to an electrically heated knife, such as is useful for cutting butter, or the like.

The appended drawing shows such 'a knife. In this drawing:

Fig. 1 is a top plan view.

Fig. 2 isa side view.

Fig. 3 is a side View with a cover part removed i or purposes of clarity.

The electrically heated knife herein disclosed comprises a C frame I, integrally molded with a handle portion II having a deep recess I2 whose open side is normally closed by a cover I3 held on to the handle by screws, or the like, I4. In the recess l2 of the handle body, which recess has extensions I5 and IS, are disposed respectively dry cells I8, a bimetal element I9, a slidable switch whose button is shown at 2S), and a flexible connector 2I for electrically connecting the positive pole of one cell to the negative pole of ano other.

The bimetal element ISI, connected to the cells, is adapted to warp, upon being heated by the passage of current therethrough, slightly to the left in Fig. 3, space for this purpose being afforded by the recess portion I5. The free end of the bimetal element I9 is connected to one end 22 of a ine resistance cutting wire 23. The other end 24 of the wire 23 is connected by soldering, or the like, to a metal band 25 running around the exterior of the C frame to serve as an ornamental band. Band 25 also serves as a means for electrically connecting the wire 23 to the switch whose contact plate 26, engaging one cell I8, is also formed to engage the terminal 21 of the band 25. The switch is a sliding switch and in the position shown establishes a circuit at the breaking point 21, so that current from the cells passes through the bimetal I9, the wire 23, the band 25, and the switch plate 26 in a complete circuit.

The shoulders 28 and 29 of the handle body are marked On and Oifj respectively, to indicate the position of theswitch button 20 and the condition of the switch.

The band is disposed in a groove 3I around two sides of the C frame I0, and staggered notches 32 on opposite sides of the groove are provided to facilitate molding of the groove in the same molding operation with the molding of the entire handle, body and C frame.

The bimetal element I9 warps to compensate for the increase of the length of the wire `under the influence of the heat caused by the passing of current through the bimetal and the wire,

and thus preserves the wire taut during the use of the tool.

A means not shown may be provided to maintain the switch 20 normally open, with such means being overcome only by and when the thumb of the operator is resting upon the switch button to keep it in the on position with contact plate 26 of the switch engaged with the band terminal 21.

It will be observed that the construction oi the device is such that replacement of the cells, or of the bimetal, or of the wire 23, or of the switch 20, is a very simple matter. Particularly in the case of the cell, it is merely necessary to remove the screws I4, remove the cover I3, and pull out the used cells from the recess I2 and reinsert new ones and this may be done without requiring the services of a skilled electrician.

Now having described the knife herein disclosed, reference should be had to the claims which follow.

I claim:

l. An electrically heated knife comprising a C frame having a handle, a ine resistance cutting wire extending across the ends of the C frame, dry cells in the handle, a bimetal, the other end of the wire being connected to the C frame, mounted on one end of the C frame and connected to one end of the wire and also connected to the dry cells, a band connected to the other end of the wire, and a switch connecting the band vto the dry cells, the bimetal being arranged to warp when heated in a direction to stretch the wire and maintain it taut and thus compensate for the expansion of lthe wire when heated, which expansion, but for the compensating effect of the bimetal, would loosen the wire.

2. An electrically heated knife comprising a C frame having a handle, a fine resistance cutting wire extending across the ends of the C frame, dry cells in the handle, a bimetal, the other end of the wire being connected to the C frame, mounted on one end of the C frame and connected to one end of the wire and also connected to the dry cells, a band connected to the other end oi ythe wire, and a switch connecting the band to the dry cells, the bimetal being arranged to warp when heated in a direction to stretch the wire and maintain it taut and thus compensate for the expansion of the wire when heated, which expansion, but for the compensating effect of the bimetal, would loosen the wire, the band being ex- I posed and extending around the C frame to serve as an ornament.

THOMAS F. SAFFADY. 

